The invention relates to a combustion-driven working tool, which is configured as a setting tool for fastening elements, a guide cylinder axially displaceable relative to the device housing; a piston mounted displaceably in the guide cylinder; a stop integral with the device housing, which projects into the guide cylinder to delimit an engagement of the piston in the direction of advance of the piston when the guide cylinder is shifted in the direction of advance of the piston; and an elastic adjusting element, which is tensions upon moving the guide cylinder into the device housing and by virtue of which, after extension of the guide cylinder out of the device housing an engagement part for engagement of the piston can be driven opposite to the direction of advance of the piston. It can be a working tool operated using fuel gas or a working tool operated using powder charge, to which cartridges are supplied.
In a conventional device, the extension movement of the device is used for piston return. Stated more precisely, for this purpose after execution of a setting operation, by means of a spring, a guide cylinder receiving the piston is moved forward; that is, towards the muzzle of the working tool or in the direction of advance of the piston, relative to the housing. Then, engaging parts or latches attached to the housing hold the piston back such that upon the extension movement of the guide cylinder, it moves rearward into its starting position; that is, in the direction opposite to that of the direction of advance of the piston.
In this solution, the drawback is that for resetting a specific piston stroke, the extension/contact movement must correspond at least to the length of the piston stroke. The contact stroke is accordingly relatively large. If the stroke is kept small, only short piston strokes can be executed.